From patchwork Thu Jul 6 14:42:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 13303802 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D03FC04A6A for ; Thu, 6 Jul 2023 14:45:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231255AbjGFOpQ (ORCPT ); Thu, 6 Jul 2023 10:45:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231895AbjGFOpN (ORCPT ); Thu, 6 Jul 2023 10:45:13 -0400 Received: from frasgout13.his.huawei.com (unknown [14.137.139.46]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F62D199F; Thu, 6 Jul 2023 07:45:10 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.18.147.227]) by frasgout13.his.huawei.com (SkyGuard) with ESMTP id 4QxfDL74Rpz9xFGL; Thu, 6 Jul 2023 22:34:10 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwAHQg0y06ZkPxkwBA--.58122S2; Thu, 06 Jul 2023 15:44:25 +0100 (CET) From: Roberto Sassu To: dhowells@redhat.com, dwmw2@infradead.org, herbert@gondor.apana.org.au, davem@davemloft.net, jarkko@kernel.org, song@kernel.org, jolsa@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, rostedt@goodmis.org, mhiramat@kernel.org, mykolal@fb.com, shuah@kernel.org Cc: linux-kernel@vger.kernel.org, keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, pbrobinson@gmail.com, zbyszek@in.waw.pl, zohar@linux.ibm.com, linux-integrity@vger.kernel.org, paul@paul-moore.com, linux-security-module@vger.kernel.org, wiktor@metacode.biz, devel@lists.sequoia-pgp.org, gnupg-devel@gnupg.org, ebiggers@kernel.org, Jason@zx2c4.com, mail@maciej.szmigiero.name, antony@vennard.ch, konstantin@linuxfoundation.org, James.Bottomley@HansenPartnership.com, Roberto Sassu Subject: [RFC][PATCH 00/10] KEYS: Introduce user asymmetric keys and signatures Date: Thu, 6 Jul 2023 16:42:13 +0200 Message-Id: <20230706144225.1046544-1-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-CM-TRANSID: LxC2BwAHQg0y06ZkPxkwBA--.58122S2 X-Coremail-Antispam: 1UD129KBjvJXoW3JFyDJFyUWrW7XryxWF13CFg_yoW3Xw15pF Z5KrWrtryktr1xKayrAw4Iga1rZr1Fyay3Kwnakw15AasIqr18ArWIkF45ur9ayF48WF1F vrsav34UKw18t3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVWxJVW8Jr1l84ACjcxK6I8E87Iv6xkF7I 0E14v26r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8C rVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4 IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCF04k2 0xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI 8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Wrv_Gr1UMIIYrxkI7VAKI48J MIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMI IF0xvE42xK8VAvwI8IcIk0rVWrJr0_WFyUJwCI42IY6I8E87Iv67AKxVW8JVWxJwCI42IY 6I8E87Iv6xkF7I0E14v26r4UJVWxJrUvcSsGvfC2KfnxnUUI43ZEXa7IU1c4S7UUUUU== X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQAKBF1jj4-V4AAAsE X-CFilter-Loop: Reflected Precedence: bulk List-ID: From: Roberto Sassu Define a new TLV-based format for keys and signatures, aiming to store and use in the kernel the crypto material from other unsupported formats (e.g. PGP). TLV fields have been defined to fill the corresponding kernel structures public_key, public_key_signature and key_preparsed_payload. Keys: struct public_key { struct key_preparsed_payload { KEY_PUB --> void *key; u32 keylen; --> prep->payload.data[asym_crypto] KEY_ALGO --> const char *pkey_algo; KEY_KID0 KEY_KID1 --> prep->payload.data[asym_key_ids] KEY_KID2 KEY_DESC --> prep->description Signatures: struct public_key_signature { SIG_S --> u8 *s; u32 s_size; SIG_KEY_ALGO --> const char *pkey_algo; SIG_HASH_ALGO --> const char *hash_algo; u32 digest_size; SIG_ENC --> const char *encoding; SIG_KID0 SIG_KID1 --> struct asymmetric_key_id *auth_ids[3]; SIG_KID2 For keys, since the format conversion has to be done in user space, user space is assumed to be trusted, in this proposal. Without this assumption, a malicious conversion tool could make a user load to the kernel a different key than the one expected. That should not be a particular problem for keys that are embedded in the kernel image and loaded at boot, since the conversion happens in a trusted environment such as the building infrastructure of the Linux distribution vendor. In the other cases, such as enrolling a key through the Machine Owner Key (MOK) mechanism, the user is responsible to ensure that the crypto material carried in the original format remains the same after the conversion. For signatures, assuming the strength of the crypto algorithms, altering the crypto material is simply a Denial-of-Service (DoS), as data can be validated only with the right signature. This patch set also offers the following contributions: - An API similar to the PKCS#7 one, to verify the authenticity of system data through user asymmetric keys and signatures - A mechanism to store a keyring blob in the kernel image and to extract and load the keys at system boot - eBPF binding, so that data authenticity verification with user asymmetric keys and signatures can be carried out also with eBPF programs - A new command for gnupg (in user space), to convert keys and signatures from PGP to the new kernel format The primary use case for this patch set is to verify the authenticity of RPM package headers with the PGP keys of the Linux distribution. Once their authenticity is verified, file digests can be extracted from those RPM headers and used as reference values for IMA Appraisal. Compared to the previous patch set, the main difference is not relying on User Mode Drivers (UMDs) for the conversion from the original format to the kernel format, due to the concern that full isolation of the UMD process cannot be achieved against a fully privileged system user (root). The discussion is still ongoing here: https://lore.kernel.org/linux-integrity/eb31920bd00e2c921b0aa6ebed8745cb0130b0e1.camel@huaweicloud.com/ This however does not prevent the goal mentioned above of verifying the authenticity of RPM headers to be achieved. The fact that Linux distribution vendors do the conversion in their infrastructure is a good enough guarantee. A very quick way to test the patch set is to execute: # gpg --conv-kernel /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-rawhide-primary | keyctl padd asymmetric "" @u # keyctl show @u Keyring 762357580 --alswrv 0 65534 keyring: _uid.0 567216072 --als--v 0 0 \_ asymmetric: PGP: 18b8e74c Patches 1-2 preliminarly export some definitions to user space so that conversion tools can specify the right public key algorithms and signature encodings (digest algorithms are already exported). Patches 3-5 introduce the user asymmetric keys and signatures. Patches 6 introduces a system API for verifying the authenticity of system data through user asymmetric keys and signatures. Patch 7-8 introduce a mechanism to store a keyring blob with user asymmetric keys in the kernel image, and load them at system boot. Patches 9-10 introduce the eBPF binding and corresponding test (which can be enabled only after the gnupg patches are upstreamed). Patches 1-2 [GNUPG] introduce the new gpg command --conv-kernel to convert PGP keys and signatures to the new kernel format. Changelog v1: - Remove useless check in validate_key() (suggested by Yonghong) - Don't rely on User Mode Drivers for the conversion from the original format to the kernel format - Use the more extensible TLV format, instead of a fixed structure Roberto Sassu (10): crypto: Export public key algorithm information crypto: Export signature encoding information KEYS: asymmetric: Introduce a parser for user asymmetric keys and sigs KEYS: asymmetric: Introduce the user asymmetric key parser KEYS: asymmetric: Introduce the user asymmetric key signature parser verification: Add verify_uasym_signature() and verify_uasym_sig_message() KEYS: asymmetric: Preload user asymmetric keys from a keyring blob KEYS: Introduce load_uasym_keyring() bpf: Introduce bpf_verify_uasym_signature() kfunc selftests/bpf: Prepare a test for user asymmetric key signatures MAINTAINERS | 1 + certs/Kconfig | 11 + certs/Makefile | 7 + certs/system_certificates.S | 18 + certs/system_keyring.c | 166 +++++- crypto/Kconfig | 6 + crypto/Makefile | 2 + crypto/asymmetric_keys/Kconfig | 14 + crypto/asymmetric_keys/Makefile | 10 + crypto/asymmetric_keys/asymmetric_type.c | 3 +- crypto/asymmetric_keys/uasym_key_parser.c | 229 ++++++++ crypto/asymmetric_keys/uasym_key_preload.c | 99 ++++ crypto/asymmetric_keys/uasym_parser.c | 201 +++++++ crypto/asymmetric_keys/uasym_parser.h | 43 ++ crypto/asymmetric_keys/uasym_sig_parser.c | 491 ++++++++++++++++++ crypto/pub_key_info.c | 20 + crypto/sig_enc_info.c | 16 + include/crypto/pub_key_info.h | 15 + include/crypto/sig_enc_info.h | 15 + include/crypto/uasym_keys_sigs.h | 82 +++ include/keys/asymmetric-type.h | 1 + include/linux/verification.h | 50 ++ include/uapi/linux/pub_key_info.h | 22 + include/uapi/linux/sig_enc_info.h | 18 + include/uapi/linux/uasym_parser.h | 107 ++++ kernel/trace/bpf_trace.c | 68 ++- ...y_pkcs7_sig.c => verify_pkcs7_uasym_sig.c} | 159 +++++- ...s7_sig.c => test_verify_pkcs7_uasym_sig.c} | 18 +- .../testing/selftests/bpf/verify_sig_setup.sh | 82 ++- 29 files changed, 1924 insertions(+), 50 deletions(-) create mode 100644 crypto/asymmetric_keys/uasym_key_parser.c create mode 100644 crypto/asymmetric_keys/uasym_key_preload.c create mode 100644 crypto/asymmetric_keys/uasym_parser.c create mode 100644 crypto/asymmetric_keys/uasym_parser.h create mode 100644 crypto/asymmetric_keys/uasym_sig_parser.c create mode 100644 crypto/pub_key_info.c create mode 100644 crypto/sig_enc_info.c create mode 100644 include/crypto/pub_key_info.h create mode 100644 include/crypto/sig_enc_info.h create mode 100644 include/crypto/uasym_keys_sigs.h create mode 100644 include/uapi/linux/pub_key_info.h create mode 100644 include/uapi/linux/sig_enc_info.h create mode 100644 include/uapi/linux/uasym_parser.h rename tools/testing/selftests/bpf/prog_tests/{verify_pkcs7_sig.c => verify_pkcs7_uasym_sig.c} (69%) rename tools/testing/selftests/bpf/progs/{test_verify_pkcs7_sig.c => test_verify_pkcs7_uasym_sig.c} (82%)